PROJECT SUMMARY - CORE B Core B will provide materials and carry out functions essential for Projects 1-3 of this Program Project. The functions include the generation of virus and pseudovirus reagents, the introduction of mutations into relevant plasmids and genomic clones of viruses, large scale production of virus and pseudovirus. The core will also perform virological assays using to test inhibitors of virus transduction and virus infection of a variety of human and mouse cell lines. The core is an essential component of this program and will be heavily utilized by all projects.